This invention relates to improved granular flame retardant products, to a process for preparing the same, and to flammable macromolecular materials containing the improved granular flame retardant products.
It is well known in the art to use halogenated hydrocarbons to impart flame retardancy to flammable macromolecular materials. The halogenated hydrocarbons used as flame retardants are typically supplied commercially in powder form. While flame retardants in powder form provide certain advantages, such as mixing and dispersion in macromolecular materials, handling powdered materials is not without significant disadvantages. Powdered materials tend to generate a significant amount of dust which may not only be toxic, but create a safety hazard when the powders are spilled in the work areas. Hence there is a trend in the industry toward providing granulated flame retardant products which do not pose as much health and safety concerns. Such granulated products should have a size and strength which provides good dispersion in macromolecular formulations without forming a significant amount of powder or fines during granulating, handling and storage operations.
While granulated products from powders can be made by adding certain binding agents to the powders, generally the most widely used binding agents do not possess flame retardant properties. Thus when forming granulated flame retardant products, it is highly desirable to minimize or eliminate the use of binding agents which are not flame retardant. However, without binding agents, the granulated flame retardant product may not possess the desired strength, i.e. may be more friable than a granulated product made with binding agents. For purposes of this invention, the friability loss of the granulated flame retardant product is a measurement of the degree with which a sample of product crumbles or otherwise forms powder during grinding, handling, and/or transporting the product.